The prior art discloses steering columns which allow adjustment of the position of the steering wheel with respect to the chassis of the vehicle. Such position adjustment of the steering wheel makes it possible for the driver to set the optimum steering wheel position for the respective driver in order thereby to improve the ergonomics of driving and in this way enhance safety when driving the motor vehicle.
Known steering columns for motor vehicles comprise a holding element, e.g. a bracket, which is fixed on the chassis of the motor vehicle. Held on the bracket is an adjustment element, the position of which relative to the bracket can be adjusted in a predetermined range and in which the steering shaft is rotatably mounted in a known manner. Through adjustment of the position of the adjustment element in relation to the holding element, it is accordingly possible to achieve position adjustment of the steering wheel held on the steering shaft. In this case, it is a known practice for the adjustment element to be adjustable in the axial direction of the steering shaft in order correspondingly to perform longitudinal adjustment of the steering wheel position and to perform height adjustment of the adjustment element in relation to the holding element in order to perform height adjustment of the steering wheel.
In this case, the height adjustment of the steering wheel is often carried out in such a way that, on the side thereof facing away from the driver, the adjustment element is held on a pivot, about which the front part of the adjustment element can then be pivoted in order correspondingly to perform the height adjustment of the steering wheel.
It is a known practice to define the possible adjusting movements by means of a locking device in such a way that the steering wheel position remains invariable while driving and that it is possible, even when relatively high forces are introduced, such as those which are introduced when entering and alighting if the driver supports himself on the steering wheel, for example, to maintain the position in such a way that no adjustment of the adjustment element in relation to the holding element takes place.
In the event of a crash, a steering wheel is usually displaceable in an axial direction in order to be able to absorb some of the energy of the crash by deformation of a crash element, for example, if the driver strikes the steering wheel. In this way, the steering wheel is simultaneously moved out of the danger zone.
In order to avoid hindering the action of a crash mechanism known per se for longitudinal adjustment of the steering column, it is necessary for the horizontal position of the steering wheel to be substantially retained in the event of a crash. In particular, a situation in which the steering wheel rears upward in the event of a crash should be avoided.
In order to prevent such rearing of the steering wheel, the prior art discloses retaining elements comprising form-fitting elements in the form of tooth systems, which provide a form-fitting connection between the holding element and the adjustment element when the locking device is locked.
An adjustable steering column comprising a retaining element of this kind is known from DE 10 2007 003 091 B3, for example. In this case, a retaining element in the form of a toothed strip is pressed into the locking position by means of the stroke provided by a tightening pin, also referred to as a clamping pin, of the locking device. In particular, the toothed strip can be brought into engagement with toothing on the bracket side cheek by the axial movement as the steering column is locked. To ensure reliable engagement of the toothing while, on the other hand, allowing snag-free adjustment of the adjustment element in relation to the holding element in the open position, a large stroke of the clamping system is necessary, which, for its part, can result in a large lever operating angle.
In GB 2 352 284 A there is a description of a steering column comprising a retaining element which likewise comprises toothing that can be brought into engagement with toothing on the bracket side cheek as the locking device is locked. However, unlike that in the abovementioned DE 10 2007 003 091 B3, this is not brought into engagement by an axial movement in the direction of extent of the clamping pin brought about by the stroke of the locking device but is brought into engagement transversely thereto in a radial direction.